Oleuropein-Rich Jasminum Grandiflorum Flower Extract Regulates the LKB1-PGC-1α Axis Related to the Attenuation of Hepatocellular Lipid Dysmetabolism

Abstract

Diets(饮食) rich in fat are a major(主要) cause(原因) of metabolic disease(疾病), and nutritional(营养) food has been widely(广泛) used(使用) to counteract the metabolic disorders such(这样) as obesity(肥胖) and fatty(脂肪) liver(肝). The present study investigated the effects of oleuropein-enriched extract(提取物) from Jasminum grandiflorum L. flowers (OLE-JGF) in high-fat diet(饮食) (HFD)-fed mice and oleic acid(酸) (OA)-treated AML-12 cells. Treatment(治疗) of HFD-fed mice with 0.6% OLE-JGF for 8 weeks significantly reduced body and liver(肝) weights, as well as attenuating lipid dysmetabolism and hepatic steatosis. OLE-JGF administration(政府当局) prominently suppressed the mRNA expressions(表达) of monocyte chemoattractant protein(蛋白)-1 (MCP-1) and cluster of differentiation 68 (CD68), and it also downregulated acetyl-CoA carboxylase (ACC) and fatty(脂肪) acid(酸) synthase (FAS) as well as sterol-regulatory-element(元素)-binding protein(蛋白) (SREBP-1c) in the liver(肝). Meanwhile, mitochondrial DNA and uncoupling protein(蛋白) 2 (UCP2) were upregulated along with the increased expression(表达) of mitochondrial biogenic promoters including liver(肝) kinase B1 (LKB1), peroxisome proliferator–activated receptor-γ coactivator-1α (PGC-1α), nuclear(核) factor(因子)-erythroid-derived 2-like 2 (Nrf2), and mitochondrial transcription factor(因子) A (Tfam), but did not change AMP-activated protein(蛋白) kinase (AMPK) in liver(肝). The lipid droplets were decreased significantly after treatment(治疗) with 80 μM oleuropein for 24 h in OA-induced AML-12 cells. Furthermore, oleuropein significantly inhibited ACC mRNA expression(表达) and upregulated LKB1, PGC-1α, and Tfam mRNA levels, as well as increasing the binding level of LKB1 to PGC-1α promoter in OA-induced cells. These findings indicate(表明) that OLE-JGF reduces hepatic lipid deposition in HFD-fed mice, as well as the fact that OA-induced liver(肝) cells may be partly(部分) attributed to upregulation of the LKB1-PGC-1α axis, which mediates hepatic lipogenesis and mitochondrial biogenesis. Our study provides a scientific(科学) basis(基础) for the benefits and potential(潜在) use(使用) of the J. grandiflorum flower as a food supplement(补充) for the prevention(预防) and treatment(治疗) of metabolic disease(疾病).